Like many things in life, the key to good results is thorough preparation and this is certainly true of preparing bone for Maori bone carving.
The goal of bone preparation is to have a nice clean, fat free, white medium on which to carve your design so you end up with a quality finished product.
The favourite of many Maori bone carvers is beef bone and in particular the ‘shin’ because it tends to be larger and thicker than any other bone. Beef bone is also readily available (unless you live in India where the cow is sacred) and your local butcher should have a steady supply of cattle beast.
Avoid beef bones from pet shops, unless you know they are fresh, as sometimes these are roasted or smoked which leeches fats into the structure of the bone and we want to avoid this at all cost – Fresh is always best.
If it hasn’t already been done, ask your butcher to cut off the joint ‘ends so you are left with a ‘cylinder’ of shin bone. This makes it easier to clean and I’m sure your butcher won’t mind taking the couple of minutes to run it through his band-saw.
Some people get the butcher to cut the shin bone in half length-ways to make it easier to clean the marrow out but I prefer to leave the bone whole until the cleaning process is complete. That way I can study the shape and form of the bone to determine what design will work best using the natural curves and structure I have to work with.
There are many differing opinions on what method is the best for cleaning bone so I will outline the basics and give a few alternatives.
One thing everyone agrees on is that it really important to remove all traces of flesh, sinew, cartilage, and fat (including the marrow which is very fatty), in order to have a nice clean palette on which to create your carving. Any fat left on the bone will leech for years and discolour it so now is not the time to take short-cuts – it does require patience.
The process itself may seem a bit macabre but is quite simple and straight forward.
- Remove the flesh and marrow
- Boil the bones
- Scrape clean
- Cut and Air dry blanks
- De grease
Removing the Flesh and Marrow
This can be done with a sharp knife; scraping and shaving away as much of it as possible. The marrow can be pressed out initially then scrape inside of the bone using a knife or wire coat-hanger. Please remember safety first – wear leather work gloves (or a butcher’s chain glove if you can get one) and cut away from you.
Boiling the Bones
Boiling is bit of a misnomer as we actually gently simmer and soak them like a slow cook casserole. Start with cold water and gently bring them to a simmer. Using just water you can make beef stock in about two hours.
If that is not quick enough you can add some clothing soap powder or detergent and reduce this time to 90 minutes.
Quicker still is to add household ammonia to the pot and 30 -40 mins should do it. But be warned you need plenty of ventilation and a good extraction fan when using ammonia..
Scraping the Bones Clean.
This is a repeat of step one where you scrape and scrub away the remaining cooked flesh and marrow. Swap your work gloves for rubber gloves and work under running water. Use a stiff brush for the outside and bottle brush to work on the inside as it is important to remove all trace of marrow before you re-boil.
NB: Some prefer to stop at this stage (as over boiling can make bone brittle) and leave the bone outside for Mother Nature to finish the job allowing the ants and beetles to clean up and the sun to bleach the bone. This can take a couple of months so if you can’t wait that long, continue with the next step.
Re-boiling the Bones
Using clean water without any additives, repeat the ‘simmering’ process for 30 minutes to an hour. This second cook is to ensure there are no traces of any flesh, soft tissue, or fatty residue left on the bone. At this stage the water should be relatively clear at the end.
Some prefer to add bleach to this second cook to help with the cleaning and bleaching process however bleach makes the bones friable. Also, if you have used ammonia or detergent in the first cook I wouldn’t advise it as there is a high risk of creating chlorine gas which is deadly.
Cutting and Air Drying the Bone Blanks
Allow the bone to cool and air dry for a day or so before cutting. Using a saw, rough cut the shin cylinders into ‘blanks’ that you will be using for your bone carving designs.
Leave the blanks outside for a further 1-2 days in a sunny spot to air dry some more. If the weather is humid you may need to leave them out for up to seven days. The blanks need to be ‘bone-dry’ before you degrease them.
NB. Don’t leave them when your dog or other animals can get them. You will find that they won’t leave much for you to work with.
De-Greasing the Bones
This is one of the most important steps and is often overlooked. Greasy bone will leach fat over time for years to come and mar your work. The chemical to use for degreasing is high flammable ‘white spirit’ or ‘lighter fluid’ or ‘dry-cleaning fluid’ and a glass container should be used.
Some prefer to spot clean but as the fatty deposits can be deep within the structure of the bone it is best to soak the bone to remove all traces.
Soak the blanks for one to three weeks or until there are no translucent spots. Refresh the fluid when it becomes discoloured over that time. (Please be considerate and dispose of the spent fluid responsibly.)
Once all the translucent spots are gone rinse the blanks in clean white spirit and leave outside to dry and dissipate the spirit. The degreased blanks should air dry relatively quickly in a day or so.
Bleaching your Bone Carvings
The simplest method is to use Mother Nature and sun-bleach them for a couple of weeks but for those impatient ones you can use the chemical approach.
WARNING: Don’t use Chlorine bleach! This will destroy the structure of the bone and make it crumbly!
The bleaching chemical of choice is Hydrogen Peroxide (H2O2) which can be found in any Chemist/Pharmacy as an antiseptic and is used a s a tooth whitener (a bit harsh on the old gums but).
Using a 3% solution you can soak your carving by immersing it for a maximum of 10 mins then remove and air dry.
Another way to soak without immersing the bone is to use cotton wool and plastic cling film. I like this method as it is more economical
- Lay a sheet of cotton wool large enough to wrap your bone carving on a sheet of cling film.
- Soak the cotton wool with Hydrogen Peroxide and wrap your bone carving in it ensuring the solution soaked wool is in contact with every surface.
- Wrap this in the cling film to seal it and leave for an hour or so.
- Keep checking the piece until you are satisfied with the colour.
Remember to wear gloves and old clothes as H2O2 is hard on skin and fabrics and don’t do this in areas where you will get in trouble for bleach marks on surfaces, furnishings and carpet.
If you would like to learn more about cleaning bone or Maori bone carving the book “Bone Carving: A Skillbase of Techniques & Concepts” by Stephen Myhre was recommended to me and is a good NZ resourceTweet